Samsung SSD 850 EVO (120GB, 250GB, 500GB & 1TB) Review
by Kristian Vättö on December 8, 2014 10:00 AM ESTEndurance: Close to Planar MLC NAND
The big question with every new NAND generation is the endurance. We already saw 6,000 P/E cycles in the SSD 850 Pro and an amazing 40,000 P/E cycles in the SSD 845DC Pro, which proved that V-NAND provides substantially better endurance over today's planar NAND nodes. However, endurance was never really an issue with planar MLC NAND except in the enterprise space, so the 850 EVO with its TLC V-NAND offers a much more interesting insight to the capability of 3D NAND technology.
To test endurance, I put the 120GB 850 EVO through our usual endurance test suite. Basically I just used Iometer to write 128KB sequential data at queue depth of 1 to the drive while monitoring the Wear Leveling Count (WLC) and Total LBAs Written SMART values. The 'Current Value' of the WLC SMART value gives the remaining endurance as a percentage (starts from 99), whereas the 'Raw Data' value indicates the number of consumed P/E cycles. In order to estimate the endurance, I had to find the spot where the increase in 'Raw Data' value decreases the 'Current Value' by one.
| Samsung SSD 850 EVO Endurance | |
| Change in Current Wear Leveling Count Value | 6 |
| Change in Raw Wear Leveling Count Value | 128 |
| Total Data Written | 15,260GiB |
| Estimated Total Write Endurance | 254,325GiB |
| Observed Number of P/E Cycles | 1,987 |
It appears that TLC flavor of V-NAND is rated at about 2,000 P/E cycles. The raw WLC value seems to be based on the user capacity (i.e. 120GB = 1 P/E cycle) because just going by it puts the endurance at ~2,133 P/E cycles (128/0.06), but that doesn't add up with the raw NAND capacity and total data written. However, the estimated total write endurance (which is just 15,260/0.06) suggests that the NAND itself is rated at 2,000 P/E cycles, which would make sense as the number of P/E cycles is usually an even thousand and it's also inline with the increase that the 850 Pro saw (from 3,000 cycles in the 840 Pro to 6,000 cycles).
| Samsung SSD 850 EVO Lifetime Estimation | ||||
| 120GB | 250GB | 500GB | 1TB | |
| Raw NAND Capacity | 128GiB | 256GiB | 512GiB | 1024GiB |
| NAND P/E Cycles | 2,000 | |||
| Raw NAND Endurance | 250TiB | 500TiB | 1000TiB | 2000TiB |
| Lifespan with 20GiB of Host Writes per Day with 1.5x Write Amplification | 23.4 years | 46.8 years | 93.5 years | 187.0 years |
| Lifespan with 100GiB of Host Writes per Day with 3x Write Amplification | 2.3 years | 4.7 years | 9.4 years | 18.7 years |
While write endurance in client workloads was never truly an issue even with planar TLC NAND, the doubled endurance in TLC V-NAND makes it practically impossible to wear out the drive before it has become totally obsolete. Only some very extreme workloads could wear out the smaller capacities before the warranty runs out, but the 850 EVO is a wrong drive for such workloads in the first place. All in all, there should be absolutely no reason to worry about the endurance of the 850 EVO, especially given the endurance ratings Samsung is giving to the 850 EVO (75TB for 120/250GB and 150TB for 500GB/1TB).
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KAlmquist - Monday, December 8, 2014 - link
My guess is that Samsung doesn't have the ability to produce very much V-NAND. So the 850 PRO, and now the 850 EVO, are priced to encourage most people to choose SSD's from the 840 line rather than the 850 line, preventing demand for the 850 line from exceeding the supply.rms141 - Monday, December 8, 2014 - link
The absence of the Samsung 840 Pro from the Storage Bench 2013 section is pretty odd. Why wouldn't you include the previous generation's higher performing product? This is a little bit like publishing a GTX 970 review without including the GTX 780 for reference.Kristian Vättö - Tuesday, December 9, 2014 - link
You can always use the Bench tool to compare any and all drives that we have tested over the years:http://www.anandtech.com/bench/SSD/65
fokka - Monday, December 8, 2014 - link
it doesn't make much sense to complain about the msrp when the drive is just now trickling to retailers. you're probably not gonna make a good deal on a 850 evo before christmas, but the prices will come down considerably in q1/q2 2015, they always do.that said, i wouldn't mind paying a couple bucks more for a 850, compared to a 840, since it's just the all around better drive and it's lower power consumption alone makes it the better option for laptops.
pitted against an mx100 it might be a tougher sell, but let's just wait a bit for the prices to come down and give the early adopters some time to beta-test the firmware for us in the meantime.
Morawka - Tuesday, December 9, 2014 - link
Does TurboWrite, native encryption, and TRIM work in RAID 0 on the 850 EVO? Thats the only way i would invest $500+ into a SSD still bottlenecked by Sata 6hojnikb - Tuesday, December 9, 2014 - link
All of that should work with appropriate motherboard/storage drives, because drive itself is not aware whenever is in RAID or not.hojnikb - Tuesday, December 9, 2014 - link
*driverspaesan - Tuesday, December 9, 2014 - link
I just got a 1TB 840 evo for $369. No way the 850 evo is worth the extra $100.R3MF - Tuesday, December 9, 2014 - link
How do you conduct this review of a perfomance oriented SSD without discussing:1. m.2 format (or lack thereof)?
2. PCIe 3.0 4x m.2 performance (vs SATA 6G)?
3. NVME m.2 performance (vs SATA 6G)?
It is the end of 2014, who seriously spends £320 on a 1TB performance SSD without considering the high-speed m.2 drives just around the corner, to which a growing number of enthusiasts have empty slots on their shiny new motherboards?
hojnikb - Tuesday, December 9, 2014 - link
>How do you conduct this review of a perfomance oriented SSD without discussing:EVO is not a performance oriented drive. 850PRO is. And this was already discussed in other reviews/seperate articles.